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ThesisItem Open Access Growth performance of crossbred calves fed molasses and probiotics supplemented diet(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2020) Ahmed, Sanidur; Bordoloi, Jyoti PrasadThe present experiment was conducted to investigate the effect of feeding molasses and probiotics on the growth performance of crossbred dairy calves. Twelve healthy crossbred calves of both sexes of similar age and body weight were allocated to two experimental groups, control (T0) and treatment (T1) with six animals in each group. Calves of both groups were fed with a standard basal diet consisting of concentrate, green fodder, and paddy straw along with Molasses @ 3% of DM requirement and multi-strain probiotics @10 gm/animal/day daily in the treatment group. The experiment was conducted as a feeding trial for six fortnights and a digestibility trial thereafter for five days in the two experimental groups. The average initial and final body weight in the 6th fortnight of the calves were 89.500±7.843 and 89.500±8.290 kg and 110.667±7.932 and 119.500±7.178 kg respectively in T0 and T1 groups. Analysis of variance of the data did not reveal any significant difference (P>0.05) in average body weight in the control (T0) and treatment (T1) groups. The overall mean daily body weight gain is 0.357±0.019 kg in the treatment group (T1) which was significantly (P<0.01) higher than the control group which is 0.252 ± 0.013 kg. In respect of different fortnights, the Average daily gain was significantly (P<0.01) higher from the 4th to 6th fortnight. Similarly, the overall fortnightly body weight gain was significantly higher (P<0.01) in the treatment group (5.000 ± 0.270 kg) than in the control group (3.556 ± 0.171 kg) of calves. The fortnightly body weight gain was higher (P<0.01) in the treatment group than in the control group from the 2nd to 6th fortnight. The overall mean values of the conformation traits (cm) in the control group (T0 ) and treatment group (T1) groups respectively were: 97.17± 1.21 and 99.08 ±1.15 cm for body length; 111.69 ±1.12 and 112.64± 1.06 cm for chest girth as well as 100.23± 0.90 and 100.85 ±0.86 cm for height at wither. All the conformation traits revealed a highly positive correlation with body weight. Analysis of variance of conformation traits showed no significant (P>0.05) difference between control (T0) and treatment (T1) groups respectively. The overall average daily DM intake was 2.76 ± 0.09 kg in the control group (T0) and 2.84 ± 0.09 kg in the treatment group (T1). Feeding of Molasses and multistrain probiotics had a positive effect on dry matter intake in the treatment group and it was higher than the control group in all fortnights. However, analysis of variance results revealed no significant (P>0.05) difference between the average values of DM intake between control (T0) and treatment (T1) groups. The overall mean values of the feed-eating time were 243.21±0.58 min. in the control (T0) and 240.42±0.54 min. in the treatment (T1) group. Analysis of variance revealed that there was a significant (P<0.05) difference between overall average feed-eating time in the control (T0) and treatment (T1) groups. The feed-eating time was reduced significantly (P<0.05) in the treatment group (T1) from the 2nd to 6th fortnight. The average FCR values were 11.77 ± 0.79 and 10.89 ± 1.00 in 1st fortnight and 10.74 ± 0.39 and 6.39 ± 0.68 in the 6th fortnight in control (T0) and treatment (T1) groups respectively. On an overall basis, FCR values were 10.89 ± 0.24 and 8.35 ± 0.40 in the control (T0) and treatment (T1) groups. Analysis of variance revealed that there was a highly significant (P<0.01) effect of supplementation of Molasses and probiotics ii on the feed conversion ratio(FCR) of the experimental animals. Further, the C.D. test revealed that the FCR in the treatment (T1) group was significantly reduced from the 3rd fortnight to the 6th fortnight compared to the control (T0) group. The overall mean values of the physiological parameters in the T0 and T1 groups respectively were as: respiration rate, 26.17 ± 0.09 and 26.45 ± 0.11 breath per minute; pulse rate, 72.04± 0.13 and 72.00 ±0.12 beats per minute and rectal temperature, 101.07± 0.11 and 100.95± 0.11(oF). Analysis of the variance of the data revealed no significant (P>0.05) difference in respect of the three parameters between the control (T0) and treatment (T1) groups. . The blood biochemical and hematological parameters like. serum glucose, serum total protein, and hemoglobin were within the normal range for crossbred calves in both the control and treatment groups and the data did not reveal any significant difference (P>0.05). The average digestibility coefficient (%) in T0 and T1 groups respectively were: 67.47±0.26 and 73.33±0.44 for dry matter (DM); 70.37±1.55 and 76.17±0.44 for organic matter (OM); 66.67±0.73 and 71.67±0.44 for crude protein (CP); 66.40±0.49 and 72.63±0.27 for ether extract (EE); 63.97±0.27 and 72.37±0.18 for crude fibre (CF) and 73.40 ±1.06 and 79.26±0.73 for nitrogen-free extract (NFE). Analysis of the data revealed significantly (P<0.01) higher digestibility of the organic nutrients in molasses and probiotics fed treatment (T1) group than control (T0) group. The economic analysis of the cost of feeding the experimental calves revealed the following: (i) average daily cost of feed consumption (on DM basis) per calf was Rs. 42.53 and Rs. 49.06, (ii) average net cost of feed consumption (on DM basis) per calf were Rs. 3572.81 and Rs. 4121.04, (iii) cost of feeding per kg body weight gain was Rs. 167.50 and Rs. 137.37 in control (T0) and treatment (T1) respectively. From the results, it was observed that the total cost of feeding was a little higher in the treatment group than in the control group. However, the total body weight gain was higher in the treatment group (T1) than in the control group (T0) which resulted in a lower cost of feeding per kg weight gain in the treatment than in the control group.ThesisItem Open Access MANAGEMENT OF GREATER WAX MOTH, Galleria mellonella (LEPIDOPTERA: PYRALIDAE) AND CHARACTERIZATION OF ITS GUT BACTERIA(2020) Rokozeno; Deka, Mukul KumarField and laboratory experiments were carried out at the Department of Entomology and Department of Agricultural Biotechnology, Assam Agricultural University, Jorhat during 2018 and 2019 to study the management of greater wax moth, Galleria mellonella (Lepidoptera: Pyralidae), a serious pest of the honey bee using different integrated modules and to characterized the gut bacterial community. Different life stages of the wax moth were studied to provide a concise information on the population trend. Laboratory studies confirmed the occurrence of multiple generations of G. mellonella in a year. In the present study, five generations of G. mellonella were recorded in a single year. The duration of each developmental stages showed variation in each generation. Mean incubation period was found to be 4.60 ± 0.49 days (1st generation), 4.40 ± 0.49 days (2nd generation), 3.20 ± 0.40 days (3rd generation), 4.20 ± 0.75 days (4th generation) and 8.00 ± 0.63 days in the 5th generation. Throughout each generation a total 6 (six) numbers of larval instars were recorded. Mean duration of the total larval period was observed to be 32.40 ± 2.33 days (1st generation), 25.20 ± 0.40 days (2nd generation), 25.40 ± 1.62 days (3rd generation), 25.60 ± 1.36 days (4th generation) and 45.80 ± 1.17 days (5th generation). The mean duration of the pre- pupal period was recorded to be 5.20 ± 0.75 days (1st generation), 3.40 ± 0.49 days (2nd generation), 3.80 ± 0.75 days (3rd generation), 4.20 ± 0.40 days (4th generation) and 10.60 ± 0.80 days (5th generation). The mean duration of the pupal period was found to be 9.80 ± 1.17 days (1st generation), 9.60 ± 0.49 days (2nd generation), 8.00 ± 0.63 days (3rd generation), 8.60 ± 0.49 days (4th generation) and 18.00 ± 1.67 days in the last generation. The longevity of the male adult wax moth recorded a mean duration of 17.80 ± 0.75 days (1st generation), 20.60 ± 1.02 days (2nd generation), 20.20 ± 0.75 days (3rd generation), 21.40 ± 1.02 days (4th generation) and 8.40 ± 0.80 days (5th generation).The adults recorded a longer period of longevity over the adult female moths. The longevity of the adult female moth recorded a mean duration of 10.40 ± 2.33 days (1st generation), 11.40 ± 1.85 days (2nd generation), 11.20 ± 0.40 days (3rd generation), 11.20 ± 0.40 days (4th generation) and 13.40 ± 1.02 days (5th generation). The larval stages of wax moth are the damaging stage of the pest, in order to manage them, different integrated module incorporating cultural, biological and cold treatment was carried out. In determining the effectiveness of different integrated modules, all the treatments were found to be effective over the control. Combs kept in deep freezer at - 7°C recorded least damage of 1.53 per cent comb in the initial period however, with the elapsing of time Bt. var. kurstaki at 1 per cent in module III(b) proved to be better over the other modules. Pertaining to larval mortality, Bt. var. kurstaki at 1 per cent showed highest mortality as compared to the other modules and exhibited mortality per cent up to 36.66 per cent. In the context of reducing adult emergence as a measure of managing wax moth, the least per cent adult emergence of 33.33 per cent was recorded in module III where Bt. var. kurstaki @1 per cent was incorporated. All the modules comparatively showed satisfactory performance in managing the wax moth over the control in which no external intervention was employed. For best preventive measures all the modules can be suggested, with emphasis on regular and timely monitoring. For an effective and desirable management, module III with Bt. var. kurstaki at 1 per cent would be recommended against the pest. G. mellonella larva has been reportedly known to degrade polyethylene (PE), as such it has been assumed that certain microbes residing in the gut may be responsible. The investigation of the gut led to the isolation of 14 microbial isolates. The morphological characteristics of the fourteen isolates were mostly circular in shape, and had an entire margin, the colony color was chiefly white with raised elevation and exhibited smooth surface. Utilising 16S rRNA sequencing and analysing them on BLAST, the isolates were identified: it constituted of thirteen numbers of bacteria and one microalgae. The bacterial species ascertained were shown to be 2 strains of Acinetobacter radioresistens, 2 strains of Bacillus circulans, 2 strains of Enterococcus faecalis, Agrobacterium sp., Exiguobacterium aestuarii, Microbacterium zeae, Microbacterium paraoxydans, Sphingomonas pseudosanguinis, Sphingobium yanoikuyae, and one number of uncultured bacterium. The lone algae out of the 14 (fourteen) microbes isolated was confirmed as Picochlorum oklahomensis. A number of the above species has been reportedly known to degrade aromatic hydrocarbon, low density polyethylene, high density polyethylene, polystyrene etc. The precise mechanism of this microbes in degrading PE, function of the host i.e. G. mellonella larva and the microbes in degrading the plastic whether individually or together, merits further investigation. The process of PE degradation could be used to devise a biotechnological solution on an industrial scale for managing polyethylene waste.ThesisItem Open Access BIOPROSPECTING ACTINOBACTERIA OF ASSAM FOR SOME RICE DISEASE MANAGEMENT AND GROWTH PROMOTION(2020-01) Gogoi, Nripen Kumar; Bora, L.C.Actinobacteria, an important group of Gram positive bacteria are potent producers of wide variety of secondary metabolites with diverse biological activities including biocontrol and plant growth promotion abilities. The members of the genus Streptomyces are especially prolific as they alone constitute 50% of the total soil actinobacteria and 18% of all biologically active secondary metabolites(nearly 7600 out of 43,000) known so far. The present investigation was undertaken to explore potent actinobacterial strains to contain two major rice diseases viz. sheath blight (ShB) and bacterial leaf blight (BLB). Total seventy five isolates of actinobacteria were isolated and their morphological, biochemical and molecular characterization were carried out. Among twelve antagonistic actinobacterial isolates observed in vitro, isolate ‘Act 116’ and ‘Act 119’recorded the maximum inhibition of ShB pathogen Rhizoctonia solani and BLB pathogen Xanthomonas oryzae pv. oryzae by 66.7% and 26.3%, respectively. Scanning electron microscopy of these two isolates showed rectiflexible and retinaculiaperti type of polysporous spore chains. Molecular identification of ‘Act116’ and ‘Act 119’ done through 16S rRNA gene sequencing revealed the strains as Streptomyces corchorusii and S. sasae, respectively. The partial gene sequences of the two isolates were submitted to NCBI GenBank (GenBank No.KY393359.1 & GenBank No. MH988751.1). The pot culture and field experiments showed significant reduction of per cent disease index (PDI) of ShB and BLB of rice (cv. Mahsuri) in strain ‘Act 116’ and ‘Act 119’ treated plants. The application of actinobacteria ‘Act 116’ and ‘Act 119’ as seed treatment, root dip and foliar spray could reduce PDI of ShB and BLB to 24.6% and 30.8%, respectively over control (70.4 and 66.7 PDI, respectively). These combinations were also resulted in significant plant growth promotion. In field experiments, the microbial population increased in treated plots compared to control. Significant uptake of nitrogen, phosphorous and potash were observed in actinobacteria treated plots compared to control. The crude bioactive compounds extracted were analyzed through LCMS and revealed the possible presence of antibiotic compounds like Difloxacin, Dicloxacillin, Nystatin, Tetracycline and Doxycyline. Hence, it can be inferred from the present study that actinobacterial strains ‘Act 116’ and ‘Act 119’ have significant biocontrol potential against the two major rice diseases ShB and BLB, respectively and can be efficient candidates for management of other plant diseases also.ThesisItem Open Access REGULATION OF MICROBIAL DYNAMICS AND NUTRIENT STATUS IN THE RICE MICRO-ECOSYSTEM DUE TO APPLICATION OF BIOAGENTS FOR MANAGEMENT OF BACTERIAL BLIGHT OF RICE (Xanthomonas oryzae pv. oryzae)(2020-01) Khan, Parveen; Bora, L. C.The present study was made to evaluate an ecofriendly management strategy using different microbe based bioformulations, viz., Bioveer (Talc based formulation of T. viride), Biotime (Talc based formulation of M. anisopliae, P. fluorescens and T. harzianum), Biogreen (Talc based formulation of T. viride, P. fluorescens, B. thuringiensis, B. bassiana and M. anisopliae), Biosona (Talc based formulation of B. bassiana) and Biofor-Pf (Vermicompost based formulation of T. harzianum and P. fluorescens) for management of bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae (Xoo). Regulation of microbial dynamics and nutrient status in rice micro-ecosytem due to application of these bioformulations was also assessed. About 30 isolates of Xoo were collected, of which Xoo2 was selected for further experimentations, due to its aggressiveness in causing BB in rice. In vitro efficacy results revealed that Bioveer was significantly highest in inhibiting the growth of Xoo (54.14%). Field evaluation of bioformulations against BB showed lowest disease incidence (29.20%) and disease severity (29.43%) when Biogreen was applied as seed treatment, seedling root dip treatment and foliar application @ 2% along with enhancement in rice grain yield (31.06 q/ha) and plant growth parameters. The total phenol content (23.16%) was significantly highest in rice leaves treated with Biogreen @ 2%. Moreover, Biogreen @ 2% was most effective in increasing the nutrient availability and uptake in rice plants and enhancing the microbial biomass carbon and soil enzyme activity. Population dynamics study of both endophytic and rhizospheric microbes revealed that maximum colonization frequency of both bacterial and fungal dynamics was associated in rice plots treated with talc based bioformulation Biogreen @ 2%. The study also revealed higher count of bacterial diversity as compared to fungal diversity. Two endophytic (EPK 5 and EPK 10) and rhizospheric (RPK 2 and RPK 8) microbes showed maximum inhibition against Xoo in vitro, which were found compatible among each other. Based on morphological, cultural, biochemical and molecular gene sequencing studies, the isolate EPK 5 was identified as Pseudomonas fluorescens, RPK 2 as Bacillus amyloliquefaciens, EPK 10 as Trichoderma asperellum and isolate RPK 8 as Talaromyces flavus. Compatible combination of these microbes could inhibit the growth of Xoo in vitro. Five best compatible combinations were tested for in planta along with a Biogreen @ 2% for suppression of BB. Studies revealed that combination of EPK 5 (P. fluorescens) + EPK 10 (T. asperellum) + RPK 2 (B. amyloliquifaciens) + RPK 8 (T. flavus) showed lowest BB incidence (17.75%) with highest grain yield (46.74 g/plant) and growth attributing characters.ThesisItem Open Access EFFECT OF GROWTH REGULATORS ON ASSAM LEMON (Citrus limon L)(2020-07) Bakhtari, Wahedullah; Kotoky, U.An experiment was conducted on Assam Lemon (Citrus limon L.) at the Experimental Farm, Department of Horticulture, Assam Agricultural University, Jorhat during 2018-2019 to study the “Effect of growth regulators on Assam Lemon (Citrus limon L)”. Six treatments with four replications were laid out in a Randomized Block Design. The treatments comprised of GA3 (60, 80 and 100ppm) and NAA (30, 40 and 50ppm). The growth regulators were applied as foliar spray at three growth stages: (1) at pre flowering stage in the month of November, 2018, (2) at flowering stage and (3) one month after fruit set. The plant growth regulators showed significant response on flowering. The minimum number of days (52.67days) was recorded in T2 (GA3 80ppm) from the date of plant growth regulators application and the highest number of days were required in case of T6 treatment (NAA 50ppm). The highest number of flowers per plant (476.74), highest fruit set (81.32%) and the lowest fruit drop (18.50%) was recorded from T2 (GA3 80ppm) during the experiment. Number of fruits per plant was recorded highest in GA2 80ppm (371.33) and the lowest in T6 (NAA 50ppm). The highest fruit weight (136.53g), fruit length (10.00cm), fruit girth (15.93 cm), fruit volume (162.89cc) and yield (52.72 t/ha) were recorded in T2 (GA3 80ppm) while the lowest values were recorded in T6 (NAA 50ppm). The results revealed that, pulp weight and pulp-peel ratio were significantly influenced by growth regulator applications. The highest pulp weight (108.32g) and the highest pulp-peel ratio (4.83) were recorded in T2 (GA3 80ppm). Peel thickness was lowest (0.48cm) in T2 (GA3 80ppm) and the highest of 0.73cm was recorded in T6 (NAA 50ppm).The results revealed that, T2 (GA3 80ppm) took the lowest number of days required for flowering to harvesting (102.47 days) and the highest (133.77 days) in T6 (NAA 50ppm). Regarding the total leaf chlorophyll content, the highest was recorded (1.29mg/g of fresh weight) in T2 (GA3 80ppm). However, there were no significant differences in leaf nitrogen and leaf phosphorous among the treatments. Highest leaf potassium (1.69%) was recorded in T1 (GA3 60ppm). The highest juice content (37.29cc) was recorded in T2 (GA3 80ppm). The highest TSS (5.18°Brix), titrable acidity (3.50%) and TSS-Acidity ratio (1.48) was recorded in T1 (GA3 60ppm), whereas, the lowest values were recorded in T6 (NAA 50ppm). From the results of the ascorbic acid content (32.15mg/100ml) the highest was recorded in T2 (GA3 80ppm). Regarding evaluation of the economics of cultivation, it can be concluded that, the highest benefit-cost ratio of 3.52 was obtained from T2 (GA3 80ppm) followed by 3.44 from T1 (GA3 60ppm). The lowest B:C ratio (2.41) was recorded in T6 (NAA 50ppm). Thus, it can be suggested that, GA3 at 80ppm is the most economical plant growth regulator to improve flowering, yield and quality of Assam Lemon.ThesisItem Open Access Agrobacterium mediated genetic transformation of Citrus reticulata cv. Khasi mandarin(2020-02) Bhandari, Sangeeta; Singh, SalvinderCitrus is number one fruit of the world on accounts of its high nutritional value. India is the fourth largest producer of Citrus in the world. The north-eastern region of India is a rich treasure of various Citrus species. Khasi mandarin is the most economically important one and plays a vital role in the socio-economic development of the people in this region. Khasi mandarins are declining at a very high rate due to its vulnerability to different pathogen and insect/ pest. Conventional breeding for overcoming these problems are limited in Citrus and are directly associated with the reproductive biology of Citrus. Recent advances in genetic engineering have made it possible to incorporate desirable genes from elite genotype mainly through Agrobacterium-mediated genetic transformation. Citrus species showed varied response to in vitro regeneration and genetic transformation. Cultivar specific optimization of in vitro regeneration and transformation protocol is very important. In the present investigation, in vitro regeneration and Agrobacterium mediated genetic transformation protocol for Khasi Mandarin was optimized using different explants like epicotyl, hypocotyl, nodal and inter nodal segment obtained from six-week-old in vitro grown zygotic seedling. Explants were transformed wih Agrobacterium strain LBA4404, harbouring plasmid pBI121-AtSUC-GUS containing nptII as a selectable marker and gus as a reporter gene. Hypocotyl was found to be the best explants for khasi mandarin transformation and regeneration. MS medium supplemented with BAP (2mg/L), NAA (0.5 mg/L), 2, 4-D (1mg/L), MES (0.5g/L), sucrose (30g/L) and acetosyringone (100μM) was found to be best medium for co-cultivation. Modified MS medium containing BAP (4mg/L), MES (0.5g/L), sucrose (30g/L), phytagel (4g/L), kanamycin (50mg/L) and timentin (150mg/L) showed highest regeneration efficiency (18%). Modified MS medium containing BAP (4mg/L), GA3 (0.5mg/L), MES (0.5g/L), sucrose (30g/L), phytagel (4g/L), kanamycin (50mg/L) and timentin (150mg/L) showed highest multiple shoot induction (6%). In vitro regenerated shoots that survived up to 3rd selection cycle were subjected to GUS assay for confirmation of GUS expression in the phloem tissues. Present investigation is a preliminary study for optimization of an in vitro regeneration and genetic transformation protocol in Khasi Mandarin.ThesisItem Open Access Food- web interaction and community structure of cabbage ecosystem(2020-01) Sarma, Daizy; Saikia, D. K.Field experiment were carried out in the Experimental Farm, Department of Horticulture, Assam Agricultural University, Jorhat during rabi 2017-18 and 2018-19 to study the food web interaction and community structure of cabbage ecosystem. Major insect pests recorded during both the crop season from 20 DAP, were cabbage aphid, Brevicoryne brassicae (L.), diamondback moth, Plutella xylostella (L.), cabbage butterfly, Pieris canidia (L.), cutworm, Agrotis ipsilon (Hfn.), cabbage looper Trichoplusia ni (Hubner) and flea beetle, Monolepta signata Oliv with minor pests viz., sawfly, Athalia proxima, cabbage head borer, Hellula undalis (L.), handmaiden moth , Syntomoides imaon (L.), epilachna beetle, Epilachna spp. (L.) and green stink bug, Nezara viridula (L) were also persisted on the crop right from the seedling stage to harvesting of the crop. Six numbers of predators viz., Coccinella transversalis (F.), Maenochilus sexmaculatus C. septempunctata (L.), Micraspis discolor (F), Harmonia dimidiata (F), Episyrphus belteotus (L.) and one number of predatory spider, Oxyopes spp. were recorded from cabbage ecosystem. In the present investigation, among different insect pests encountered in the field, B. brassicae showed the highest relative abundance ( 28.78%) on HYV and 29.65% for hybrid variety followed by A. ipsilon (20.45% for HYV and 17.65% on hybrid) during 2017-18 and same trend also found during 2018-19. Different weather parameters related to the correlation study indicated that the minimum temperature had negative significant impact with the population build up of B. brassicae (r= -0.652), P. canidia (r= -0.638), T. ni (r= -0.627) and M. signata (r= -0.596), whereas, BSSH showed positive significant effect with A. ipsilon (r= 0.620) in HYV variety. In case of hybrid variety, all major insect pests and predators showed negative significant effect with minimum temperature except T. ni during 2017-18. During 2018-19, a negative significant correlation was observed in between insect pests and predators associated to local and hybrid variety. The correlation of B. brassicae and coccinellid predators for both varieties showed a significant positive impact for 2017-18 and 2018-19. The different physiomorphic, biochemical parameters and the number of insect pests and predators for both the varieties were at par with each other during 2017-18 and 2018-19. Glucosinolate, phenol and Flavonoid content showed a negative association with major insect pests and predators for both the varieties during the investigation of 2017-19. The diversity study of insect pests in different phenological stages of cabbage indicated highest species diversity and evenness during the pre heading stage of cabbage followed by heading stage whereas, highest species richness was recorded during seedling stage for both the varieties during 2017-18 and 2018-19. In case of distribution pattern, a contagious distribution (both HYV and hybrid variety) was assessed for insect pests and their natural enemies during the present investigation. The consumption of aphids by C. transversalis, when applied individually and in different combination showed that highest consumption rate of 133.40±2.25 was observed in C. transversalis (Adult) x C. transversalis (Adult) followed by C. transversalis (Adult) x C. transversalis (4th) and C. transversalis (Adult)x C. transversalis (3rd ) with 104.90±2.25 and 99.10±2.25, respectively. In case of Consumption of aphids by M. sexmaculatus, highest result was observed in M. sexmaculatus (Adult) x M. sexmaculatus (Adult) combination with 96.26 ±3.60. Consumption of aphids when applied C. transversalis and M. sexmaculatus in different combination, highest consumption rate of 109.10 ± 2.37 was found in C. transversalis (Adult) x M. sexmaculatus (Adult). Intraspecific cannibalism among different instars and adult of C. transversalis and M. sexmaculatus in absence of prey was the highest in C. transversalis (Adult) x C. transversalis (3rd) combination where as, C. transversalis (Adult) consumed only 33.30%. In case of Interspecific predation among different instars and adult of C. transversalis and M. sexmaculatus in absence of prey, C. transversalis (Adult) showed highest consumption rate of 40.00% followed by C. transversalis (4th) with 33.30%.ThesisItem Open Access DNA POLYMORPHISM IN MITOCHONDRIAL GENES ENCODING ND1, CO1 AND CYTB IN CANINE MALIGNANT TUMOURS(College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2020-01) REHMAN, SHAKEEL-UL; Borah, ProbodhMalignant tumours in dogs are frequently reported. The types of malignancies commonly reported in canines include female breast cancers, lymphomas, adenomas and carcinomas of mast cells. Specific mutations and polymorphism in mitochondrial genes have been shown to be associated with different types of human malignancies. However, similar studies in respect to malignant tumours in dogs are very limited. Hence in the present study, an attempt was made to identify frequency of occurrence of mutation and polymorphism in gene sequences encoding NADH dehydrogenase subunit 1 (ND1), cytochrome b (CYTB) fragments of mtDNA and cytochrome c oxidase subunit 1 (CO1) in dogs, and to define the association of DNA polymorphic mutations with different tumour types. Based on histopathology, out of 10 tumours examined 5 (50%) were found to be of epithelial and the rest 5 (50%) of mesenchymal origin. Two of the five epithelial tumors were recognized as adenonocarcinoma and three as squamous cell carcinoma. Of the five mesenchymal tumors, four were identified as fibrosarcoma and one as liposarcoma. Of the 10 cases, 8 (80%) were recorded in local and 2 (20%) in crossbred dogs. While 7 (70%) cases were recorded in male, 3 (30%) were observed in females. Location-wise, two each of the tumours were observed in skin and mammary gland, while one each was observed in mouth, left flank, abdominal region, testicle, right elbow and left forelimb. The dogs suffering from the neoplastic growth in different parts of the body were within the range of 5 - 13 years of age. Analysis of three mtDNA gene fragments established a relatively low level of molecular genetic variation between the tissues (tumour tissue, normal tissue and blood) of the individuals examined. Majority of the mutational changes in the ND1, COI and CYTB gene fragments in the analyzed tissues in most of the dogs with tumours were insertions and deletions. Only a few polymorphisms were noted in the partial gene fragments of the analyzed tissues when compared to reference successions. Multiple substitutions and insertions have been noted in ND1 gene fragment; these included four substitutions (C218T, T455C, G498A and C666T) and three insertions (341InsC, 355InsC and 718InsT). However, no mutations were recorded in ND1 gene fragment from any of the three types of tissues examined in case of a dog affected with squamous cell carcinoma. Changes in CYTB gene fragment included two substitutions (C322T and T799C) and one insertion (303InsG) mutation. Polymorphism C322T in the CYTB fragment was noted in 40% of the samples analysed. No mutation was, however, detected in this gene fragment in one case of fibrosarcoma. In the COI gene fragment, A735G polymorphic mutation was recorded in all (100%) the 10 cases of malignant tumours investigated in the present study. In this gene fragment, instances of mutations recorded were comparatively lesser. Except for C218T mutation observed in ND1 gene fragment seven cases of canine malignant tumour that induced S (Serine) to Y (Tyrosine) variation in the amino acid sequence of the coded protein at position 72, no other substitution mutation recorded in this gene fragment could cause a variation at the level of amino acid sequence. On the other hand, none of the mutations detected in CYTB gene fragment could induce any change in the level of amino acid sequence of the coded protein. Similarly, the only substitution mutation in the CO1 gene fragment that induced a change at the amino acid level was A813T mutation observed in a case of fibrosarcoma, which caused a G (Glycine) to A (Alanine) variation at 71 position. Results of the present study showed the effect of two alleles (ND1: 218, CO1: 813) on the amino acid sequence of the coded proteins which suggested consequently their potential role in carcinogenesis. However, the sample size in the present study was too small to infer conclusively about the association of the mutations and polymorphisms identified in the present study with specific malignant tumours in dog.ThesisItem Open Access ECOLOGY OF APHID VECTORS OF CITRUS TRISTEZA VIRUS(2020-07) CHANGKIRI, MAONGKAR T.; Patgiri, P.A field survey was conducted to study the incidence of citrus tristeza virus (CTV) and its aphid vectors, in different citrus growing locations of Assam and Nagaland. 190 samples were collected from four districts of Assam (Jorhat, Tinsukia, Sivasagar and Golaghat) and two districts of Nagaland (Mokokchung and Wokha). Citrus leaf samples were used for detection of CTV infection by double antibody sandwich-enzyme linked immuno-sorbent assay (DASELISA) and Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). According to the results, 75 per cent CTV disease incidence was detected in surveyed areas of Assam and 24.55 per cent CTV disease incidence was detected in Nagaland. District wise, the highest CTV disease incidence (96.67 %) was detected in Tinsukia district of Assam and the lowest (21.43 %) was detected in Mokokchung district of Nagaland. RT-PCR confirmed the results of DASELISA. The survey result also indicated the presence of the vector Toxoptera citricida in all the locations. The elevations of the different location surveyed ranged from 79-1130 m AMSL. The study on population dynamics of T. citricida, revealed that the aphid reached its highest peak population of 416.68 on the 4th of June, during 2017 and 431.28 on 15th May, during 2018. T. citricida was observed to have two population peaks per year. The minimum temperature was the most dominant factor which showed positive and significant correlation, for mean population of T. citricida. 15 species of coccinellid predators and one species of syrphid were observed in the field plot of Assam Lemon and Micraspis discolor, Cheilomenes sexmaculata, Coelophora bisellata and Coelophora saucia, were the most abundant and they were found actively feeding on T. citricida. The population of T. citricida, showed positive and significant correlation, with all four coccinellid beetles, indicating that the populations of the predators, increased or decreased with the abundance or scarcity of T. citricida. The data on the two year study of the biology of the four coccinellid beetles revealed that the longest incubation period (3.43 ± 0.07 days) was recorded on C. sexmaculata. The longest total larval period (11.52 ± 0.26 days) was recorded on C. sexmaculata. The longest pupal period (3.90 ± 0.08 days) was recorded on C. sexmaculata. The longest total developmental (egg to adult emergence) period was recorded on C. sexmaculata, with an average duration of 18.85 ± 0.31. C. sexmaculata had the longest adult longevity with an average of 50.90 ± 1.16 days and the longest total life cycle (69.75 ± 1.17 days) was recorded on C. sexmaculata. Pooled data analysis of the two year study of predatory efficiency of the four coccinellid beetles reared on T. citricida, indicated that there was significant difference among the different predators. It was observed that the feeding potential of all the beetles increased gradually through each larval stage with the fourth being the most voracious. The predatory efficiency of the larval stages of the four coccinellid beetles from highest to lowest was recorded in the following order. C. sexmaculata (27.04 ± 0.32) > C. bissellata (24.63 ± 0.23) > C. saucia (23.44 ± 0.26) > M. discolor (20.13 ± 0.17). The predatory efficiency of the adult stages of the four coccinellid beetles from highest to lowest was recorded in the following order. C. saucia (82.66 ± 0.69) > C. bissellata (78.94 ± 0.81) > C. sexmaculata (66.36 ± 0.83) > M. discolor (53.01 ± 0.59).
